Properties of ion debris emitted from laser-produced mass-limited tin plasmas for extreme ultraviolet light source applications

\Properties of ion debris emitted from laser-produced mass-limited tin plasmas have been experimentally investigated for an application to extreme ultraviolet (EUV) lithography. Simple scaling laws to design the mass-limited target, which is a key technique to minimize contamination of the first EUV collection mirror, is discussed. The measured energy spectrum of the tin ions is consistent with a prediction by the isothermal expansion model. The average charge state of the tin ions is evaluated to be +5 at 180 mm away from the plasma, and higher-energy ions have higher charge state. It was found that not only EUV emission but also ion energy spectra are sensitively affected by the target mass limitation. (c) 2005 American Institute of Physics.